1. Field of the Invention
The present invention is broadly concerned with calcium-enriched compositions and methods of supplementing food products with those compositions. More particularly, the inventive compositions include respective sources of phosphate ions, citrate ions, and calcium ions, a metal hydroxide, and water. The compositions have high solids contents and are in the form of substantially uniform, colloidal suspensions in which a high percentage of the available calcium ions remains dispersed.
2. Description of the Prior Art
The food industry has long sought stable, water-dispersible forms of calcium which would allow significant amounts of calcium to be introduced into food products without substantially increasing the bulk of the product. To be effective in this context, the calcium-containing substances must be essentially odorless, colorless, tasteless, and producible at a relatively low cost. In addition, these substances must be stable under the extreme conditions dictated by formulation, processing, and storage of the food products.
Numerous food products would benefit from calcium enrichment. For example, animal milk products (particularly those formed from cow""s milk) are already considered to be a good dietary source of calcium. However, these products contain only limited quantities of calcium in each serving, requiring the average person to consume a large portion of the product to obtain the recommended daily allowance (RDA) of calcium. Furthermore, some people have medical conditions (e.g., osteoporosis) which require the consumption of calcium beyond that required for others. Therefore, supplemental products which increase the amount of calcium in each serving of milk products at a low cost and without negatively affecting the quality of the milk product are always in demand.
Many people do not consume animal milk products for one reason or another. For example, some people are allergic to these products and cannot safely consume them. There are other people who simply do not consume animal milk products as a lifestyle choice. Many of these people turn to soy milk as an alternative to animal milk products. While the taste and odor of soy milk has been substantially improved in recent years, soy milk does not naturally contain a significant amount of calcium. Thus, soy milk must be supplemented with calcium in order to provide many of these people with at least some calcium in their diets.
Certainly, many calcium supplements have been attempted in the past. The majority of the prior art calcium-enriched products are deficient in that they have extremely low solids contents, leading to products which are mostly water and is thus costly to ship and store. However, when the moisture levels of these products are reduced in order to make shipping and storing more feasible, the calcium generally precipitates out of solution, forming an unappealing sediment.
The present invention overcomes these problems by broadly providing calcium-enriched compositions having high solids contents of soluble calcium with very little or no sedimentation. It has been discovered that the order of mixing the various ingredients in forming the composition is critical, and thus, modifying the mixing order followed in prior art methods dramatically increases the solids contents of soluble calcium in the composition.
In more detail, the inventive compositions comprise a source of phosphate ions, a source of citrate ions, a source of calcium ions, a quantity of a metal hydroxide, and water. The source of phosphate ions should be provided in sufficient quantities so that the composition comprises from about 5-28% by weight phosphate ions, and preferably from about 8-23% by weight phosphate ions, based upon the total weight of the solids in the composition taken as 100% by weight. The preferred sources of phosphate ions are phosphoric and polyphosphoric acids.
The source of citrate ions should be present in the composition at such a level that the composition comprises from about 5-32% by weight citrate ions, and preferably from about 8-25% by weight citrate ions, based upon the total weight of the solids in the composition taken as 100% by weight. The preferred sources of citrate ions are those selected from the group consisting of citric acid, calcium citrate, potassium citrate, and mixtures thereof, with citric acid being the most preferred source of citrate ions.
In combination with the foregoing citrate and phosphate ion concentrations, each of these concentrations should also be such that the molar ratio of citrate ions to phosphate ions is from about 1.0:1.35 to about 1.0:2.35, and preferably from about 1.0:1.75 to about 1.0:1.95. These ratios are important for obtaining the improved solids contents and calcium yields of the inventive compositions.
The source of calcium ions should be utilized in sufficient quantities to provide from about 2.5-16.5% by weight calcium ions, and preferably from about 4-15% by weight calcium ions, based upon the total weight of the solids in the composition taken as 100% by weight. Preferred sources of calcium ions are those selected from the group consisting of calcium hydroxide, calcium carbonate, calcium oxide, and mixtures thereof. The most preferred sources of calcium ions are calcium hydroxide and calcium oxide.
The metal hydroxide is preferably included in sufficient quantities in the compositions such that the compositions comprise from about 0.5-7.5% by weight of the metal ions, and more preferably from about 0.8-6.5% by weight of the metal ions, based upon the total weight of the solids in the composition taken as 100% by weight. Preferably the metal hydroxide is an alkali metal hydroxide, with potassium hydroxide and sodium hydroxide being particularly preferred.
Finally, water should be included in the composition at a level of from about 0.1-80% by weight, and preferably from about 2.0-50% by weight, based upon the total weight of the composition taken as 100% by weight.
The inventive compositions are prepared by forming a precursor mixture comprising the source of citrate ions, the source of calcium ions, the metal hydroxide, and water. The order of addition of these ingredients during this stage is not critical, although it is preferred that the calcium ion source be added to the water initially, followed by the addition of the metal hydroxide and then the citrate ion source to the resulting mixture. Preferably, mixing is carried out on the intermediate mixtures for about 2-3 minutes after the addition of each ingredient.
The source of phosphate ions is then added to the precursor mixture, followed by intense mixing and heating of the resulting composition to a temperature of about 190-210xc2x0 F., and preferably about 200xc2x0 F. until the desired solids content is achieved. That is, the solids content of the inventive compositions is at least about 20% by weight, preferably at least about 35% by weight, and more preferably at least about 45% by weight, based upon the total weight of the composition taken as 100% by weight. It has been discovered that adding the source of phosphate ions to the formed precursor mixture (i.e., after the source of citrate ions has been mixed with the other ingredients) dramatically increases the level of soluble solids in the composition, making these high solids contents obtainable. This improvement substantially lessens the quantity of moisture in the composition that must be shipped and stored and, therefore, will lessen the cost of shipping and storing the compositions.
The resulting compositions have a pH of from about 5.5-7.5, and preferably from about 6.5-7.0. Furthermore, the final compositions comprise at least about 3% by weight calcium ions, and preferably at least about 6% by weight calcium ions, based upon the total weight of the composition taken as 100% by weight. This high calcium ion concentration is a result of the fact that at least about 70%, preferably at least about 80%, and more preferably at least about 90% of the theoretically available quantity of calcium ions will remain dispersed in the unshaken composition (i.e., a composition that has been maintained essentially motionless for at least about 2 days) at ambient temperatures.
In applications where it is desired to produce a dry, reconstitutable product, it is generally preferred to subject the above-described aqueous composition to a drying process (e.g., spray drying or drum drying) until the moisture in the product has been reduced to a level of less than about 5% by weight, and preferably less than about 1% by weight, based upon the total weight of the composition taken as 100% by weight. The resultant solid powder, flake, or granular product can then be reconstituted in aqueous media by mixing it with water at levels of 1 part product with from about 1-4 parts water to form a composition which will exhibit substantially identical properties as those described above with respect to the original aqueous composition.
It will be appreciated that the inventive compositions (either in the concentrated or dried forms) are well-suited for supplementing food products with calcium. Preferred food products which can be supplemented with the calcium-enriched compositions include: dairy products such as milk (e.g., cow""s milk) and sour cream; imitation dairy products such as soy milk; soy-based products (e.g., tofu); beverages such as coffee, tea, water, fruit juices, vegetable juices, and other carbonated or non-carbonated beverages; soups; infant foods (e.g., infant formula, baby food); and pureed foods (e.g., applesauce). Other preferred food products include animal foods (e.g., dog food, cat food), mineral or nutritional supplements, mineral tonics, condiments, syrup, sauces (e.g., spaghetti sauce), and dessert products (e.g., pudding, ice cream, whipped topping). Those skilled in the art will appreciate that virtually any product, food or otherwise, in need of calcium supplementation can be enriched according to the invention.
Advantageously, these food products can be supplemented by simply mixing the composition (either aqueous or dried) with the food product under ambient conditions. The supplemented products can be formulated to provide at least 100% of the RDA of calcium (i.e., 1000 mg of calcium ions per day is the RDA, thus, 1000 mg of calcium ions per quart of product would provide 100% of the RDA) or as much as 200% of the RDA of calcium, depending on the serving size. Thus, the food product can be supplemented to contain at least about 100 mg, preferably at least about 500 mg, and more preferably at least about 1000 mg, more calcium ions per serving (e.g., per liter or per gram of food product) than would otherwise be present in the non-supplemented product. This is preferably accomplished by mixing from about 12-60 cc of the aqueous composition or from about 6.0-12.0 g of the dried composition with each liter of food product to be supplemented.